Spiders use 3D vision to pounce on prey

Researchers at the Osaka City University have solved one of the darndest arachnid mysteries: how the relatively simple nervous systems of spiders allow some of them to perform cat-like attacks and razor-sharp pounces on their prey.

In a report published in the journal Science, researchers looked at how a particular spider, Adansons jumping spider, has the ability to jump huge distances with high accuracy.

For we homo sapiens, blurry vision gets in the way of all sorts of things. But according to Science, for "some spiders, however, images are deliberately defocused on the retina to provide for the crucial depth perception that allows high-precision jumps."

Said Wired:

“What’s the point of having a retina that’s out of focus?” The answer, it turns out, is that having two versions of the same scene—one crisp and one fuzzy—helps spiders gauge the distance to objects like fruit flies and other prey.

Scientists blacked out some of the spiders' eyes and tested how accurately they jumped under different colors of light. Spiders are color blind to red and green in the different blurry and sharp retinas of their complex eyes, the researchers measured their jump accuracy before concluding that the blurriness helps calculate depth.

So the next time a spider jumps on you, beware: he sees you much better than you see him.